Melanoma cells have the ability to switch to a dedifferentiated, invasive phenotype in response to multiple stimuli. Here, we show that exposure of melanomas to multiple stresses including BRAF-MEK ...inhibitor therapy, hypoxia, and UV irradiation leads to an increase in histone deacetylase 8 (HDAC8) activity and the adoption of a drug-resistant phenotype. Mass spectrometry-based phosphoproteomics implicated HDAC8 in the regulation of MAPK and AP-1 signaling. Introduction of HDAC8 into drug-naïve melanoma cells conveyed resistance both
and
. HDAC8-mediated BRAF inhibitor resistance was mediated via receptor tyrosine kinase activation, leading to MAPK signaling. Although HDACs function at the histone level, they also regulate nonhistone substrates, and introduction of HDAC8 decreased the acetylation of c-Jun, increasing its transcriptional activity and enriching for an AP-1 gene signature. Mutation of the putative c-Jun acetylation site at lysine 273 increased transcriptional activation of c-Jun in melanoma cells and conveyed resistance to BRAF inhibition.
xenograft studies confirmed the key role of HDAC8 in therapeutic adaptation, with both nonselective and HDAC8-specific inhibitors enhancing the durability of BRAF inhibitor therapy. Our studies demonstrate that HDAC8-specific inhibitors limit the adaptation of melanoma cells to multiple stresses including BRAF-MEK inhibition. SIGNIFICANCE: This study provides evidence that HDAC8 drives transcriptional plasticity in melanoma cells in response to a range of stresses through direct deacetylation of c-Jun.
http://cancerres.aacrjournals.org/content/canres/79/11/2947/F1.large.jpg.
This study addresses the role of PTEN loss in intrinsic resistance to the BRAF inhibitor PLX4720. Immunohistochemical staining of a tissue array covering all stages of melanocytic neoplasia (n = 192) ...revealed PTEN expression to be lost in >10% of all melanoma cases. Although PTEN expression status did not predict for sensitivity to the growth inhibitory effects of PLX4720, it was predictive for apoptosis, with only limited cell death observed in melanomas lacking PTEN expression (PTEN-). Mechanistically, PLX4720 was found to stimulate AKT signaling in the PTEN- but not the PTEN+ cell lines. Liquid chromatography multiple reaction monitoring mass spectrometry (LC-MRM) was performed to identify differences in apoptosis signaling between the two cell line groups. PLX4720 treatment significantly increased BIM expression in the PTEN+ (>14-fold) compared with the PTEN- cell lines (four-fold). A role for PTEN in the regulation of PLX4720-mediated BIM expression was confirmed by siRNA knockdown of PTEN and through reintroduction of PTEN into cells that were PTEN-. Further studies showed that siRNA knockdown of BIM significantly blunted the apoptotic response in PTEN+ melanoma cells. Dual treatment of PTEN- cells with PLX4720 and a PI3K inhibitor enhanced BIM expression at both the mRNA and protein level and increased the level of apoptosis through a mechanism involving AKT3 and the activation of FOXO3a. In conclusion, we have shown for the first time that loss of PTEN contributes to intrinsic BRAF inhibitor resistance via the suppression of BIM-mediated apoptosis.
To provide guidance to clinicians regarding the use of systemic therapy for melanoma.
ASCO convened an Expert Panel and conducted a systematic review of the literature.
A systematic review, one ...meta-analysis, and 34 additional randomized trials were identified. The published studies included a wide range of systemic therapies in cutaneous and noncutaneous melanoma.
In the adjuvant setting, nivolumab or pembrolizumab should be offered to patients with resected stage IIIA/B/C/D
wild-type cutaneous melanoma, while either of those two agents or the combination of dabrafenib and trametinib should be offered in
-mutant disease. No recommendation could be made for or against the use of neoadjuvant therapy in cutaneous melanoma. In the unresectable/metastatic setting, ipilimumab plus nivolumab, nivolumab alone, or pembrolizumab alone should be offered to patients with
wild-type cutaneous melanoma, while those three regimens or combination BRAF/MEK inhibitor therapy with dabrafenib/trametinib, encorafenib/binimetinib, or vemurafenib/cobimetinib should be offered in
-mutant disease. Patients with mucosal melanoma may be offered the same therapies recommended for cutaneous melanoma. No recommendation could be made for or against specific therapy for uveal melanoma. Additional information is available at www.asco.org/melanoma-guidelines.
Gene-based immunotherapy for cancer is limited by the lack of safe, efficient, reproducible, and titratable delivery methods. Direct injection of DNA into tissue, although safer than viral vectors, ...suffers from low gene transfer efficiency. In vivo electroporation, in preclinical models, significantly enhances gene transfer efficiency while retaining the safety advantages of plasmid DNA.
A phase I dose escalation trial of plasmid interleukin (IL)-12 electroporation was carried out in patients with metastatic melanoma. Patients received electroporation on days 1, 5, and 8 during a single 39-day cycle, into metastatic melanoma lesions with six 100-mus pulses at a 1,300-V/cm electric field through a penetrating six-electrode array immediately after DNA injection. Pre- and post-treatment biopsies were obtained at defined time points for detailed histologic evaluation and determination of IL-12 protein levels.
Twenty-four patients were treated at seven dose levels, with minimal systemic toxicity. Transient pain after electroporation was the major adverse effect. Post-treatment biopsies showed plasmid dose proportional increases in IL-12 protein levels as well as marked tumor necrosis and lymphocytic infiltrate. Two (10%) of 19 patients with nonelectroporated distant lesions and no other systemic therapy showed complete regression of all metastases, whereas eight additional patients (42%) showed disease stabilization or partial response.
This report describes the first human trial, to our knowledge, of gene transfer utilizing in vivo DNA electroporation. The results indicated this modality to be safe, effective, reproducible, and titratable.
Lay Summary
Pathologists sometimes have great difficulty in determining whether a mole biopsied from the skin of a child is benign or malignant.
New molecular technologies have helped pathologists to ...identify pediatric melanomas, but there are still some atypical moles that cannot be definitively classified as benign or malignant.
With further research, it is hoped that the number of these atypical tumors can be decreased and that the treatment for all children with moles and melanoma can be improved.
Molecular genetic techniques have broadened our understanding of the diagnostic classification of pediatric melanoma and atypical melanocytic proliferations such as Spitz tumors. These techniques should be incorporated into standard approaches to diagnosing and classifying atypical or malignant pediatric melanocytic lesions.
Indications for sentinel lymph node biopsy (SLNB) for thin melanoma are continually evolving. We present a large multi-institutional study to determine factors predictive of sentinel lymph node (SLN) ...metastasis in thin melanoma.
Retrospective review of the Sentinel Lymph Node Working Group database from 1994 to 2012 identified 1,250 patients who had an SLNB and thin melanomas (≤ 1 mm). Clinicopathologic characteristics were correlated with SLN status and outcome.
SLN metastases were detected in 65 (5.2%) of 1,250 patients. On univariable analysis, rates of Breslow thickness ≥ 0.75 mm, Clark level ≥ IV, ulceration, and absence of regression differed significantly between positive and negative SLN groups (all P < .05). These four variables and mitotic rate were used in multivariable analysis, which demonstrated that Breslow thickness ≥ 0.75 mm (P = .03), Clark level ≥ IV (P = .05), and ulceration (P = .01) significantly predicted SLN metastasis with 6.3%, 7.0%, and 11.6% of the patients with these respective characteristics having SLN disease. Melanomas < 0.75 mm had positive SLN rates of < 5% regardless of Clark level and ulceration status. Median follow-up was 2.6 years. Melanoma-specific survival was significantly worse for patients with positive versus negative SLNs (P = .001).
Breslow thickness ≥ 0.75 mm, Clark level ≥ IV, and ulceration significantly predict SLN disease in thin melanoma. Most SLN metastases (86.2%) occur in melanomas ≥ 0.75 mm, with 6.3% of these patients having SLN disease, whereas in melanomas < 0.75 mm, SLN metastasis rates are < 5%. By using a 5% metastasis risk threshold, SLNB is indicated for melanomas ≥ 0.75 mm, but further study is needed to define indications for SLNB in melanomas < 0.75 mm.
Granulocyte macrophage colony-stimulating factor (GM-CSF) can induce differentiation of dendritic cells (DCs) in preclinical models. We hypothesized that GM-CSF-stimulated DC differentiation may ...result in clinical benefit in patients with high-risk melanoma.
We conducted a prospective trial in patients with high-risk (stage III B/C, IV), resected melanoma, with GM-CSF 125 microg/m(2)/d administered for 14 days every 28 days. Patients underwent clinical restaging every four cycles, with DC analysis performed at baseline and at 2, 4, 8, and 12 weeks.
Of 42 patients enrolled, 39 were assessable for clinical outcome and DC analysis. Median overall survival was 65 months (95% CI, 43 to 67 months) and recurrence-free survival was 5.6 months (95% CI, 3 to 11 months). GM-CSF treatment caused an increase in mature DCs, first identified after 2 weeks of treatment, normalizing by 4 weeks. Patients with decreased DCs at baseline had significant increases in DC number and function compared with those with "normal" parameters at baseline. No change was observed in the number of myeloid-derived suppressor cells (MDSCs). Early recurrence (< 90 days) correlated with a decreased effect of GM-CSF on host DCs, compared with late or no (evidence of) recurrence.
GM-CSF treatment was associated with a transient increase in mature DCs, but not MDSCs. Greater increase of DCs was associated with remission or delayed recurrence. The prolonged overall survival observed warrants further exploration.
Phase II trials with biochemotherapy (BCT) have shown encouraging response rates in metastatic melanoma, and meta-analyses and one phase III trial have suggested a survival benefit. In an effort to ...determine the relative efficacy of BCT compared with chemotherapy alone, a phase III trial was performed within the United States Intergroup.
Patients were randomly assigned to receive cisplatin, vinblastine, and dacarbazine (CVD) either alone or concurrent with interleukin-2 and interferon alfa-2b (BCT). Treatment cycles were repeated at 21-day intervals for a maximum of four cycles. Tumor response was assessed after cycles 2 and 4, then every 3 months.
Four hundred fifteen patients were enrolled, and 395 patients (CVD, n = 195; BCT, n = 200) were deemed eligible and assessable. The two study arms were well balanced for stratification factors and other prognostic factors. Response rate was 19.5% for BCT and 13.8% for CVD (P = .140). Median progression-free survival was significantly longer for BCT than for CVD (4.8 v 2.9 months; P = .015), although this did not translate into an advantage in either median overall survival (9.0 v 8.7 months) or the percentage of patients alive at 1 year (41% v 36.9%). More patients experienced grade 3 or worse toxic events with BCT than CVD (95% v 73%; P = .001).
Although BCT produced slightly higher response rates and longer median progression-free survival than CVD alone, this was not associated with either improved overall survival or durable responses. Considering the extra toxicity and complexity, this concurrent BCT regimen cannot be recommended for patients with metastatic melanoma.
...what lessons can we learn from this failure to ensure that future phase 3 trials have the greatest chance of success, while minimising the number of patients subjected to ineffective and ...potentially toxic drugs? ...dosing schedule should not be neglected: concurrent use of immunotherapy agents in phase 3 trials should be based on confidence that the beneficial effects of a combination do not require a specific sequence of administration. ...epacadostat monotherapy has not been documented to have antitumour activity in melanoma, and it remains an unproven hypothesis that drugs without single-agent activity can improve any meaningful efficacy endpoint when combined with checkpoint blockade. If the putative partner is intended to manipulate a target that does not itself lead to tumour response, but strong laboratory evidence suggests that it could augment antitumour immunity, we should consider showing that the relevant biological activity occurs in a neoadjuvant approach with the proposed phase 3 dose.
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